Differences in mRNA populations of short and long bovine conceptuses on Day 15 of gestation

Abstract

The majority of pregnancy loss in cattle occurs between Days 8 and 16 of gestation, coincident with the initiation of conceptus elongation and the onset of maternal recognition of pregnancy. Differences in conceptus length on the same day of gestation may be related to an inherent lack of developmental competency or may simply be a consequence of asynchrony with the maternal environment. The objective of this work was to characterize differential patterns of mRNA expression between short and long bovine conceptuses recovered on Day 15 of gestation. Embryos were produced from super-ovulated Holstein donor cows, and groups of Grade-1 and Grade-3 compact morulas were transferred into recipient heifers at Day 6.5 of their cycle. Conceptuses were recovered at Day 15 of gestation, and measured to assess overall length and area. Total RNA was extracted and analyzed on individual GeneChip Bovine Genome Arrays (Affymetrix, Santa Clara, CA). Gene expression was compared between conceptuses derived from the transfer of Grade-1 versus Grade-3 embryos; no differences were identified in the profiles of Day-15 conceptuses of these different embryo grades. When gene expression was compared between conceptuses classified as either short (mean length of 4.2 ± 0.1 mm [standard error]) or long (24.7 ± 1.9 mm) upon recovery at Day 15 of gestation, a total of 348 genes were differentially expressed. Of these, 221 genes were up-regulated and 127 were down-regulated in long compared to short conceptuses. In summary, differences in gene expression were identified between conceptuses recovered on Day 15 of gestation, based on their length. These data may be used to identify genes and cellular pathways involved in enhanced conceptus elongation that could serve as markers of successful pregnancy. Mol. Reprod. Dev. 83: 424-441, 2016. © 2016 Wiley Periodicals, Inc.

Aspects of embryo-maternal communication in establishment of pregnancy in cattle

“…These data support the hypothesis that conceptus regulation of gene expression in the endometrium is complex and involves factors other than IFNT that may have a biological role in pregnancy establishment. The findings are consistent with the presence of unique proteins in ULF of pregnant heifers on Day 16 and produced by short-term in vitro cultured Day 16 conceptuses (Forde et al, 2015) and those of Bartol et al (1985) who demonstrated that the fully elongated bovine conceptus produces a significant number of proteins when cultured in vitro. Further, Spencer et al (2013) demonstrated that the bovine conceptus produces prostaglandins, which can modify the endometrium prior to pregnancy recognition.…”

“…The role of P4 in uterine receptivity is unequivocal Spencer et al, 2016). Low circulating P4 concentrations in the first week after ovulation, as frequently occurs in highproducing lactating dairy cows, are associated with under-developed conceptuses with an altered transcriptomic signature (Barnwell et al, 2016) and a low likelihood of establishing pregnancy (Wiltbank et al, 2016). On the other hand, elevated concentrations of circulating P4 in the period immediately after conception have been associated with advanced conceptus elongation (Carter et al, 2008), increased IFNT production (Mann and Lamming 2001), and greater pregnancy rates in cattle and sheep (Ashworth et al, 1989;Stronge et al, 2005;McNeill et al, 2006).…”

Interferon-tau and fertility in ruminants

“…Differences in conceptus length on the same day of gestation may be related to an inherent lack of developmental competence or may simply be a consequence of asynchrony with the maternal environment (Pope 1988). Barnwell and coworkers characterised differential patterns of mRNA expression between short (mean length of 4.2 ± 0.1 mm) and long (24.7 ± 1.9 mm) bovine conceptuses recovered on Day 15 of gestation (Barnwell et al 2016). A total of 348 genes were differentially expressed (221 genes upregulated and 127 downregulated in long compared to short conceptuses) suggesting inherent differences exist between such conceptuses and not just differences in the conceptuses's ability to produce IFNT.…”

Progesterone and conceptus-derived factors important for conceptus survival and growth

“…Analysis identified differentially regulated genes organized in nine gene clusters forming a sequential transcript dynamics across these developmental stages. These data have been expanded upon by more recent studies (Valour et al, 2014;Barnwell et al, 2015Barnwell et al, , 2016Ribeiro et al, 2016a, b). Flechon et al (1986) cut day 12 ovine blastocysts into pieces and cultured them in vitro for 24 h, to produce structures called trophoblastic vesicles (TV, blastocysts without the embryonic disc).…”

“…In this regard, Barnwell et al (2016) recently characterized differential patterns of mRNA expression between short and long bovine conceptuses recovered on day 15 of gestation which may be indicative of conceptus survival.…”